Biological weapons (“bioweapons”) include bacteria, viruses, and toxins that are dispersed deliberately in an environment to cause disease or death to humans, animals, or plants in the environment. Examples of bioweapons include Bacillus anthracis, which causes anthrax, Yersinia pestis, which causes plague, and Variola major, which causes smallpox. Bioweapons also include “biotoxins,” which are toxins produced by certain biological organisms. Exemplary biotoxins are botulinum toxin, produced by the bacterium Clostridium botulinum, and ricin isolated from castor oil seeds. Western counter-proliferation agencies currently recognize 23 types of bacteria, 43 types of viruses, and 14 types of biotoxins as potential bioweapons.
To an aggressor, bioweapons are appealing because: (a) they are directed indiscriminately to populations, (b) they leave infrastructure intact, (c) they usually are effective in very small amounts, (d) they can be produced at low cost in a short period of time, and (e) their detection is difficult. Because of these properties of bioweapons, there is growing concern that bioweapons will become the preferred weapon of mass destruction.
Recent activities by terrorists have targeted the U.S. Postal System by using common envelopes as vehicles for delivering anthrax spores. Whereas, before the current outbreak of bioterrorism-related anthrax, only 18 cases of inhalational anthrax had been reported in the United States in the 20th century, ten cases of biotcrrorism-related inhalational anthrax have now occurred. Because the U.S. Postal Service currently handles an estimated 239 billion items of mail per year, the risk is high that another disease outbreak will result from envelopes deliberately contaminated with anthrax or other bioweapon. The risk is even larger for mail and parcel services worldwide.
The U.S. Postal Service has issued a set of guidelines for evaluating suspicious mail and parcels. These include use of excessive postage, lopsidedness or oddly shaped, marked with restrictive endorsements (such as “Personal” or “Confidential”), having protruding wires, strange odors, or stains, or denoting a city or state in the postmark that does not match the return address. However, current technology can respond to bioterrorism only if such a threat is suspected or known to be imminent. Presently, there is no known practical way in which to screen all mail for bioweapons in a systematic manner.